The present invention relates to a digital broadcasting receiver capable of finding out a physical channel by reference to a channel table which provides correspondences between preset physical channels and broadcast programs (logical channels).
With a conventional TV (Television) receiver, the user is allowed to freely select and view a desired one of broadcast programs transmitted from a TV station to multiple homes. In recent years, attention has been focused on digital broadcasting which is capable of efficiently transmitting a multiplicity of programs using a limited frequency band by compression of video signals and the like, multiplex transmission and a like technique relying upon the digital compression and encoding technology.
The following description is directed to CATV (Cable Television) digital broadcasting as a representative of the digital broadcasting. In Japan for example, the CATV digital broadcasting has a maximum of four broadcasting channels (logical channels) for each of physical channels allotted to an actual CATV frequency band. Therefore, a physical channel number is not the same with an associated logical channel number in the CATV broadcasting. In Japan, the CATV digital broadcasting has a total of 113 physical channels each having a bandwidth of 6 MHz within a CATV frequency band of 93 to 767 MHz. The number of programs per physical channel is four at maximum and, hence, a total of 452 programs at maximum can be transmitted through the CATV digital broadcasting. Thus, the physical channels and the broadcast programs (logical channels) do not have a one-to-one correspondence therebetween and, therefore, the correspondence between the two does not satisfy a sufficient condition for determining a broadcast program from a physical channel selected.
In actual utilization, the user searches a CATV program table for a logical channel on which a desired broadcast program is transmitted and then instructs a CATV digital broadcasting receiver to be tuned to that logical channel via a remote controller or the like. In response to this instruction, the CATV digital broadcasting receiver references a channel table providing correspondences between preset physical channels and broadcast programs (logical channels) to find out the physical channel associated with the desired program. Subsequently, the CATV digital broadcasting receiver causes the tuner to perform channel selection based on the physical channel thus found out for digital demodulation. Further, the CATV digital broadcasting receiver extracts the broadcast program (logical channel) designated and restores image and sound to display the program on the television receiver. Thus, the operation of referencing the channel table is indispensable for the CATV digital broadcasting receiver.
Data described in the channel table (channel table data) is data transmitted from the CATV station as occasion arises. The channel table data includes data on the correspondence between a physical channel and an associated logical channel, data on the logical channel, and identification information for identifying a program to be broadcast on that logical channel in a straightforward manner. Such identification information is Source ID for example.
The aforementioned CATV digital broadcasting receiver allows the user to designate and register any desired logical channel. For example, if the user registers as a favorite channel a logical channel on which a user's favorite broadcast program is to be provided, the user can view the broadcast program immediately by merely selecting the favorite channel via a remote controller or the like without the need to check logical channels one by one in order to find out the logical channel providing the broadcast program.
A digital broadcasting receiver as described in Japanese Patent Laid-Open Publication No. 2000-115742 has been proposed.
However, the correspondences between broadcast programs and their respective logical channel numbers can often be changed due to change in program planning at the CATV station or a like factor. If the logical channel number associated with a favorite broadcast program that has been provided on the favorite channel is changed, the aforementioned CATV digital broadcasting receiver does not allow the user to view the favorite program even when the user selects the favorite channel (the logical channel that provided the favorite program before the channel number change) via the remote controller or the like.
For this reason, the user has to find out again the logical channel currently providing the favorite program in order to view the favorite program. This makes the user feel very troublesome.
The receiver described in Japanese Patent Laid-Open Publication No. 2000-115742 fails to take possible change in logical channel number into account. Therefore, this receiver also makes the user feel very troublesome, like the aforementioned CATV broadcasting receiver.
A feature of the present invention is to provide a digital broadcasting receiver configured such that even if the number of a logical channel that has been previously designated by the user as a channel providing a favorite broadcast program is replaced with an alternative logical channel number, the digital broadcasting receiver automatically selects the alternative logical channel number currently providing the favorite broadcast program.